1. Field of the Invention
The present invention relates generally to fingerprint scanning and imaging. More specifically, this invention relates to a piezoelectric film used within a fingerprint scanner.
2. Related Art
Biometrics are a group of technologies that provide a high level of security. Fingerprint capture and recognition is an important biometric technology. Law enforcement, banking, voting, and other industries increasingly rely upon fingerprints as a biometric to recognize or verify identity. See, Biometrics Explained, v. 2.0, G. Roethenbaugh, International Computer Society Assn. Carlisle, Pa. 1998, pages 1–34 (incorporated herein by reference in its entirety). A number of companies are currently active in biometric finger technologies. See, a listing of companies published by Biometric Technology Today (Btt™), two pages, 1999 (http://www.sjbresearch.com).
Optical fingerprint scanners are available that detect a reflected optical image of a fingerprint. To capture a quality image at a sufficiently high resolution, optical fingerprint scanners require at minimum optical components (e.g., lenses), an illumination source, and an imaging camera. Such components add to the overall cost of a fingerprint scanner. Mechanical structures to maintain alignment also increase manufacturing and maintenance costs.
Solid-state silicon-based transducers are also available in commercial fingerprint scanners sold by Seimens, Lucent, and Harris Semiconductor. Such silicon transducers measure capacitance. This requires the silicon transducers to be thin, reducing their durability. To detect a rolled fingerprint, the sensing array of the solid-state transducer needs to have an area of sufficient size, for example one-inch by one-inch with a thickness of about 50 microns. A silicon array with such a large size increases the base cost of a fingerprint scanner and leads to greater maintenance costs. Durability and structural integrity are also more likely to suffer in such a large silicon geometry.
What is needed is an inexpensive, durable fingerprint scanner with low maintenance costs.